The Devil's Succubus
by Way-Up-In-The-Skye
Summary: Fionna meets the Devil in a bar of all places, and learns that some parts of his reputation aren't entirely true. Fiolee. Lemon.
1. Chapter 1

**Hope you enjoy! Reviews feed my soul!**

In case you were wondering, the Devil isn't all horns and claws and world domination. Not at all, actually. If wanting money, power, and sex were the greatest sins, then practically every person on Earth would be an almighty demon lord, and the Devil would be out of a job.

Greed is only one aspect of him, and it's not a very big one. He's greedy, sure. But he lacks a certain... Ambition. But that's only natural. He's quite lazy at times.

He does have horns and claws though. But he doesn't use them very often.

You see, the only reason the Devil is in any way dangerous is that he knows he isn't righteous. And because of that, he hasn't gone insane despite existing all these millennia. When people have a sense of purpose they think is righteous, then they consider themselves righteous. They lose their minds for their purposes, believing that it must be achieved at all costs. Righteous people are easily manipulated, they'll do anything if they think what they're doing is right. The Devil can't be manipulated at all.

On the flip side, this is what makes him so benign. He has no sense of purpose. If his goals are met, well great. If his goals aren't met, he simply doesn't care. He won't extend any more effort than he sees fit, and knows when to cut his losses.

Except when it comes to lust. Then he'll stop at nothing to achieve what he wants.

That's where I come in.

_I had snuck in the back door of a bar owned by a friend's older brother to win a bet that I could prove to said friend's brother that I could drink him under a table. The guy practically kept the place open by selling to minors, since we were in a college town, so I probably could've walked in the front no problem. But I snuck through the back anyway. Don't ask me why. Stupid, I know. The whole shebang was moronic. I was a kid, cut me some slack._

_The funny thing is, I actually only had one drink. I was sitting across from this friend's brother. His name started with an "I", sounded something like Ignition, but that wasn't quite it. I know it was something as stupid as Ignition though. Anyway, I'm sitting across from him, when I get the feeling I'm being watched. So I glance over, and I see this... guy. He looked young, nineteen or twenty maybe. The dude was pale as bone, tall, kind of lanky. Wearing all black. His hair was black and messy, it was hanging low so I couldn't see his eyes. But I knew he was staring right at me. His whole body was turned toward me in fact._

_He stood up and walked toward me slowly. I heard what's-his-name say something like, "Oh forget it, you're not paying attention anyway. I gotta take a piss. Be right back." I vaguely noticed him get up right as this new guy reached me. He extended his hand in a gesture that didn't seem entirely friendly, but I took it anyway, shocked to learn that his hand was freezing. I looked up at him, his features were angular. He was clearly attractive. His voice was low and husky when he asked me, "What's your name?"_

_"F-fionna," I squeaked out. I cleared my throat and tried very hard to sound intimidating. "Yours?"_

_"You can call me... Marshall." He seemed like he made the name right on the spot. "You seem a bit young to be in here."_

_I squared my shoulders. "I could say the same to you."_

_He chuckled. "I'm a bit older than I look." He angled his head just so I could see his eyes. They were blood red._

_I'd like to say that I stood up and left right then. That I went home and never gave this Marshall guy a second thought. But that's not what happened._

_You see, there was something about him I simply couldn't bear to leave. Something in his voice, his appearance, made me want to be closer. Much, much closer._

_The desire was so great, in fact, that like an idiot with a sudden burst of confidence I said, "I'm a bit older than I look too," total lie, "so do you want to get out of here?"_

_He smirked. "Oh, I like you." I hadn't realized he was still holding onto my hand until he hauled me to my feet, and then he just stood still._

_"Aren't we-," I started to say._

_"Hang on, it takes a second," he said._

_And then, I shit you not, he snapped his fingers and we were suddenly in a different place. A bedroom, it seemed. A normal one. Not like you'd expect from the Devil (if you haven't guessed that's who this guy is by now, then I don't know how you can read at all). It had laminate wood floors, a queen sized bed with a purple quilt, whitewashed textured walls, and a desk in the corner. It looked like, well, a teenager's bedroom._

_"What the-,"_

_"It's a bit drab for the Devil's bedchambers," he said, "but I grew tired of the torches and red velvet walls a while ago. So I just adapt to the times."_

_"What the fuck?!" It felt good to finish that sentence._

_He glanced down at me. "Oh yeah, I forgot about mentioning that part. I'm the Devil. Demon extraordinaire. Don't worry, I'm not going to kill you or infect your mind and dreams or anything like that. I brought you here for sex. That's all. Honestly, I've gotten such a bad rap over the years from some of the women I've had. Spreading all these lies about me because I wouldn't let them stay. You're not going to do that though, right?"_

_What the actual fuck._

_"Look man," I said. "I had one beer, and I don't know how you slipped something into it. But if you don't take me home right now I will rip you in fucking half." I was breathing heavy, staring him down. He didn't even look phased._

_"Oh I see. You're a skeptic." His tone was bored. "Look if I'd drugged you, you wouldn't even be standing up right now, let alone be in the presence of mind to tell me off. Alright, here." He snapped his fingers again, and the lights cut out suddenly. When they cut back on, he snapped them one more time, and he floated a couple inches off the ground. When his feet were on the floor again, I did the stupidest thing anyone has ever done ever. But don't worry. It worked out pretty well for me._

_First, I said, "So I'm just here for sex, right?"_

_He nodded._

_And then I kissed the fucking Devil._

_Hard._

_And strike me down if I ever say it didn't feel damn good._

_He smirked into it, and when I broke for air, he mumbled, "Now_ we're talking."

_I kissed him again, and his hands wondered to my ass. He lifted me up, and I wrapped my legs around his waist. He backed me up to the bed and laid me down as his tongue found its way into my mouth. We fought for dominance, and surprisingly enough, I won. He ripped my shirt off. Literally ripped the damn thing in half. I broke the kiss and glared up at him, and he responded with a cheeky little grin and said, "No bra. My kind of girl. Those damn things piss me off." Then he dove his head down to my neck. His hands ran over my chest, his thumbs rubbed circles over my nipples. He kissed and licked at bit my neck and holy shit. I've never been one to moan, but I sure did then. I tugged at his shirt. And he broke away to take it off. I took the lapse in contact to take of my skirt and panties, so I could be completely naked._

_I reached up and unbuttoned his jeans. I yanked them down, and he kicked them the rest of the way off. And then everything was just skin. I didn't even get a good look at him before he was back on top of me, his lips working their way down my body. Remember how I said he was cold before? He wasn't now. The longer I was with him, the more he was heating up, until he was almost unbearably hot. His lips finally reached the apex of my legs. He parted my folds, and licked that little bundle of nerves, he worked his tongue in circles, slowly. I bucked my hips up into him, and he slowly pushed a finger inside me. Then another, and another._

_"You taste good," he mumbled. The vibrations made me feel like I was one fire. Hell, if I was on fire, I felt so good I probably wouldn't have cared. All I could reply with was a string of mutters that were more moans than words._

_Then suddenly, he pulled away. He looked at me, expectantly. I didn't get it for a second, then I rolled my eyes and said, "Let me guess, eye for an eye? That's how you operate?"_

_"If that's how you want to think about it."_

_I smiled. "If the roles reversed, I'd preach it that way."_

_I sighed a little, and bent down. I took his already hard length in my hand, and placed the tip just past my lips. I sucked lightly, and swirled my tongue. I heard him groan above me. I pushed more of him past my lips, sucking and bobbing my head. He tangled his fingers into my hair, encouraging me to quicken my pace. So I continued like that, sucking and bobbing. When he was practically vibrating in my mouth, he suddenly pulled away, then, in a blink, had me pinned beneath him._

_He didn't really ask if I was ready or anything. And I kind of don't care._

_He slammed himself inside of me. And the little sparks of pleasure I had been feeling before turned into an inferno. He wasted no time pulling away and burying himself in me again, and again, and again. He kept his head in the crook of my neck, kissing it again. My hands found their way to his back, and my nails were digging in. He didn't seem to mind. In fact he moaned every time I scratched him particularly hard. I wrapped my legs around him, not bothering to reign in the steady stream of curse words flowing from my mouth._

_It was so good, I tell you. So fucking good._

_The pleasure climbed higher and higher. I swear I was burning alive in the most wonderful way possible. Finally, I threw my head back and screamed as I came, "M-marshALL!" He followed shortly after, letting out a low growl._

_That growl was sexy as fuck._

_He picked me up and flipped us over, so I was laying on his chest. He waited for me go catch my breath, letting his hands trail patterns on my back._

_"Shit, Fionna," he said. "I'm usually a one time kind of guy. But we're going to have to do this again sometime."_

_I smirked, "Alright, how about right now."_

_"They'll wonder where you are if I keep you too long," he said._

_I sighed. "Damn. Friday, then?"_

_"Sounds good."_

Anyway, PB, that's why I haven't been coming to our study sessions. Fridays turned into Thursdays and Fridays turned into every day. So... Sorry?

... 'You're full of shit Fionna. It's not that hard to just say you're lazy dude."

It's totally true!

'Sure it is. Just tell your fictional devilish sex toy that you can't bomb another Algebra test, and that you need to make it to next week's meet up.'

But I-... Fine. Whatever.


	2. Chapter 2

**A little supplemental chapter. The reviews warmed my heart.**

"Marshall I'm serious, I have to go. If I fail another test I'm screwed."

I try very hard to ignore the fact that the Devil himself is literally trying to coax me away from doing something valuable with my time. I'll start laughing at the irony, and any laugh that comes out of me right now will sound more like a choked moan. He's standing behind me, kissing my neck softly, and has his arms wrapped around me, his fingers toying with my hip bones.

"But I want you," he whines pitifully. Some king of darkness and evil he turned out to be.

I scoff. "You've been alive for thousands of years and you still haven't figured out the most obvious truth to living? Newsflash. You don't always get what you want. And besides. You only have to wait a couple of hours. Then you've got me all to yourself."

"But-!"

"No buts. I really gotta go! If I'm late PB will skewer me alive! And it's not like I want to. I only need help in Algebra, but if I don't stay for English tutoring PB gets pissy for extending extra effort only for Phoebe. They had some sort of falling out or something... I don't know. I should be back by ten."

He sighs, removes himself from me, and plops down on on my bed. He'd started showing up at my place when he knew my older sister Cake, who looks after me, wouldn't be home. He'd said the change of scenery was nice.

"Fine," he says. "I'll just wait and suffer." He pouts like a five year old, and one of his sharp canines sticks out as he does.

"Good. I'll be back soon."

0o0o0

"So the systems of quadratic equations can be solved by using the quadratic formula to- Fionna are you even listening?!" PB's voice breaks the sound barrier, and my head snaps up. I don't know if I've been sleeping or just that far zoned out. Math has never been my strong suit. And the library chairs are making my butt numb.

"Yeah! Yeah!" I say. "Systems of equations!"

She raises a pink eyebrow. Honestly, it's one thing to dye your hair pink, but dying your eyebrows the same shade is a bit excessive.

"Oh really," she says. "Systems of what kind of equations?"

"Quadratic?" Please let me be right please let me be right please let me be right.

She nods her head, and I think I'm in the clear, but she says, "And since you've obviously been paying attention, how do you solve the system of a quadratic equation?"

I start sweating bullets. "Um... Um..."

Phoebe, who has been silent thus far, shoves PB lightly and says, "Oh lay off her. You didn't even explain that part."

Phoebe to the rescue. I shoot her a grateful look, and she sends back a nonchalant thumbs-up under the table.

PB looks at her uncomfortably, and shifts in her seat. "Right, anyway, to solve the systems of quadratic equations..."

I lose myself in the practice math problems. Once we've gone over what PB deems enough chapters and looks over my work and concludes that I should at least score and eighty-six, we move on to English. I only stay out of obligation, since I actually do pretty well in that class, and it's probably only ten seconds in before I realize I'm bored out of my fucking mind.

Luckily, I don't have to stay long.

I feel him before I see him. He has a dark aura, which I find funny. He's not really all that intimidating.

Marshall's hands are suddenly on my shoulders. He leans down, kisses my temple, looks up, and says, "Ladies."

PB and Phoebe jump in surprise.

"Who are you?" PB asks.

I can hear the smirk in his voice as he says, "I'm a... friend of Fionna's. She told me to pick her up at ten. It's a quarter to eleven, and she didn't come outside. I wanted to make sure she was okay. Here I am."

Impatient bastard...

"Shit, is it really that late?!" Phoebe exclaims. "I gotta jet. See you later Fionna... Peebles." She gathers up her stuff in a hurry and rushes off.

PB looks petulant at not getting to finish her women-of-classic-literature lecture, but says, "I guess I should go too. See you tomorrow. Oh, and by the way Fionna, I can see why you've been skipping out," her eyes are appraising Marshall, "But come on. The Devil. That's just weak."

Marshall raises an eyebrow. "You told her?"

I shrug. It's not like she believes me, and I didn't think she would, since she's all madame scientific research and shit.

She gathers her stuff as well, and I stand up and start to head out, but Marshall catches me by the wrist and whispers "Wait." with a cheeky grin on his face. He snaps his fingers, and the lights shut off. He snaps them again, and when the lights come back on, all the desks are stacked precariously on top of the excessively high bookshelves. We're lucky everyone else in the library has left for the night, and we're in an annex room away from the librarian.

PB stares at him in awe for a moment, but clears her throat and says, "I'm sure there's a completely logical explanation. Though I will admit that your boy toy is one hell of a magician. Fionna, I bid you goodnight."

Once she leaves, we bust out laughing until we're breathless.

"Oh man," I say once I've stopped gasping for air, "You actually made her doubt herself for a second. Now that's impressive."

He chuckles and says, "So can we get out of here now? You're beyond late."

I roll my eyes and walk out with him. Once we're outside, he says, "You know, I don't think I can wait."

"I live literally two blocks from here, and you could just snap your fingers you know."

"Well yeah, but where's the fun in that? Come on." He takes my hand and drags me down the dimly lit street. He pulls me into the first alley he sees, and the second we're shrouded in shadows, he slams me against the wall and kisses me roughly.

I reach up and grip his hair, tugging it hard. He hisses at me, but it's not exactly a hacked-off kind of hiss. He breaks the kiss and brings his lips to my jaw. His hand finds its way between my legs, and he strokes me gently. He breaks off and looks at me in surprise. "No panties?" he says.

I shrug innocently. "I figured you wouldn't be in the bullshit around kind of mood."

He flashes a crooked grin and says, "In that, dear Fionna, you are very correct." He continues his stroking, rubbing my clit in circles with his thumb. He pushes his remaining fingers inside of me and pumps them quickly, curling them every once in a while. I have to bite down on his shoulder to keep from crying out because holy shit. It feels beyond good. I feel like I could run a marathon, which is bogus because I'm pretty sure my legs are trembling. No. Not trembling. Trembling is for the weak. Shaking? No. Convulsing? Yeah, convulsing. That's a little better.

And I'm so close. I'm so close I can practically taste it, when I hear a shrill, yet familiar voice yell, "HEY! You can't do that out here!"

I try to spring away from him, but of course, the Devil has no shame, and keeps holding onto me, stroking me, and honestly, I stop caring about whoever's watching. So, despite our onlooker's protest, I bite deep into Marshall's shoulder and come on his fingers.

He withdraws his hand, and licks the wetness off of his fingers slowly, giving me a knowing look. Finally, the onlooker has had enough and marches over there and says, "Look, I don't know who in the hell you think you are, but you can't just have sex in the middle of- oh, well hello there."

God that voice is familiar. I turn so I'm hiding behind Marshall's form. I don't need anyone I know seeing me like this, and I'm suddenly thankful that he's so much bigger than me. I catch a glimpse of the source of the voice when I shift my position though, and-

Oh shit. That's why the voice was familiar. It belongs to my sister, Cake. I try and shrink myself and stay even further out of sight.

"Hello ma'am," Marshall says smoothly. "I apologize for the indecency. It seems that we simply can't keep our hands off each other. But we're finished here, and won't be continuing such an activity in this setting, so please, continue with the rest of your evening."

"I-I," she stammers. Oh. He's working the demon charm. Well played. Please work, please work... "Sure. Just... Just don't let me catch that again. My baby sister comes to this library all the time. I don't need the likes of you corrupting her." I try very hard not to snort as she walks away indignantly, hips swaying.

When she's gone, I breathe a sigh of relief and look at Marshall and say, "Come on, I gotta get home before she does."

He nods, and raises his hand to snap his fingers, but as he does he says, smirking, "Just remember, after she's asleep, you know the rules. Eye for an eye."

I smirk back. "You got it."


End file.
